The overall objectives of this project during the last 14 years have been to study the effect of hormones and related chemical agents on glycolysis. Our approach has been to study the nature of the glycolytic enzymes, their different molecular control mechanisms and how different hormones and related chemical agents affect their activity. We are proposing in the next 5 year grant period to study further the relationship between the structure and function of sheep heart phosphofructokinase (PFK), an important rate limiting enzyme in glycolysis, and to investigate the mechanism of action of catecholamines and related chemical agents on this enzyme. The following are specific objectives to be carried out on purified PFK from sheep heart as well as PFK in tissue extracts and protein-glycogen particles: a) to study the nature of the allosteric sites of PFK, b) to identify its different conformational isomers, c) to test the specific activity and kinetic properties of different aggregated forms of PFK, d) to investigate the controversial subject of the mechanism of action of PFK, e) to study the mechanism of inhibition of PFK by aldolase and fructose-1,6-diphosphatase, f) to study the nature of the enzyme in freshly isolated tissue extracts and in muscle protein-glycogen particles; kinetics, possible covalent modification of the enzyme during isolation and other properties, g) to continue our investigations on the effect of epinephrine, related hormones and chemical agents on PFK by itself and on the enzyme as part of the multienzyme glycolytic system.